1. Technical Field
The present application relates to an adjustable hydrocephalus valve.
2. Background Information
Background information is for informational purposes only and does not necessarily admit that subsequently mentioned information and publications are prior art.
The present application relates to an adjustable hydrocephalus valve to equalize the pressure of the fluid in the cranium of a hydrocephalus patient.
Hydrocephalus patients have the following medical problem:
In the cranium, the brain is surrounded by a special liquid called cerebrospinal fluid (CSF) or liquor. This liquor is continuously produced and reabsorbed in equal amounts. In the illness hydrocephalus (also called water on the brain), this equilibrium is disrupted and more liquid is produced than is reabsorbed. Because the interior of the skull represents a closed vessel, the result is an increase in volume. In infants, the seams in the skull cannot grow together and close, and, in adults, the internal pressure in the skull increases. Therefore there are two types of hydrocephalus: adult and infantile.
Hydrocephalus treatment initially comprised simply draining the liquor. This drainage was effected by means of a simple hose connection between the skull and a large venous blood vessel or by a corresponding connection between the skull and the abdomen via a hose. It was quickly determined, however, that the pressure in the skull must or should maintain a certain physiological value if other complications are to be prevented or minimized.
A number of different types of valves are known that are installed in the drain for the liquor, and by means of which the pressure of the liquor can be adjusted. Valves of this type are implanted under the skin in the vicinity of the head. The valves are designed to open at a certain critical pressure and to release the flow of liquor. By means of a line—which is also implanted under the skin—the liquor is drained into the upper vena cava or into the abdominal cavity.
But a satisfactory solution has not yet been achieved with known valves.
The adjustment to the patient in question, i.e. to the particular application case, is lacking.
Valve developments that allow an adjustment are already known.
The valves in question are implanted in the patient and, for example, drain the excess liquor from the patient's skull via a tube line, which is likewise implanted, and empty, for example, into a vena cava or into the abdomen. The valve pressure is thereby determined by a spring, wherein the spring is adjusted by means of a mechanism that has a pivoting or rotating part that is moved from outside by pivoting or rotating the magnets, so that the spring is wound up or released.
The known valves have a more or less flat construction. The objective of the flat construction is to prevent or minimize bumps or protuberances on the patient's head to the maximum extent possible as a result of the implant procedure.
Some valves include, for example, the Codman Medos valve.
This valve is a ball valve with a spring-loaded ball. The valve is adjusted by changing the position of the spring. The spring presses with one end on the valve ball. With the other end, the spring is braced against an abutment. In this model, the height of the abutment can be adjusted by rotation. The height can be adjusted because the abutment is rotational and is provided on top with an inclined or step-wise edge along which the spring glides. The adjustment range of the abutment is limited to a rotational movement of the abutment of maximum one hundred eighty degrees.
This leads to inaccuracies in the adjustment. In addition, a slight unintended rotational movement of the abutment can already lead to considerable valve modifications.
The Sophysa valve is also one of the known valves.
Even the manufacturer of this valve warns that the hydrocephalus patient should avoid or minimize coming into contact with permanent or substantially permanent magnets in toys, headsets, loudspeakers and electromagnetic fields of the type that are emitted by electric motors, electric shavers, hair dryers, switches, etc. This warning from the manufacturer comprises a warning against most areas of everyday life. As a person is unable nowadays to evade exposure to such things, proposed solutions of this kind are generally impractical.
In the meantime some efforts have been made to improve the valves. An example of a valve is disclosed in U.S. Pat. No. 7,422,566 (inventor Christoph Miethke), which patent is incorporated by reference herein.
Some valves retain the known constructional design and have the objective to increase the safety of such valves.
In some valves, greater safety is achieved in two ways.
The first way includes an adjustment of the spring. In this regard, a possibly large adjustment path is provided, which is accompanied in a change in the spring loading. This means that a greater adjustment path is provided for a comparable modification range of the spring loading. To the extent in which the adjustment path becomes larger, the above expressed danger of an unwanted adjustment is reduced.
Possibly, the accuracy of the adjustment is simultaneously or substantially simultaneously increased as the adjustment travel becomes greater.
Some valves comprise magnetically actuated locking as the other way to greater security.
The possibility for a larger design of the adjustment path results from the modification of the location of the spring. In some valves, the spring is placed such that the plane of movement of the spring, when it is adjusted, lies parallel or substantially parallel to the plane, in which the pivotable movement or rotational movement of the rotating part/rotor takes place. In this regard, the parallelism also occurs if the planes coincide.
As a result of the possible arrangement of the spring, the spring can move in the direction in which the valve housing has the largest dimension. This is in the direction of the flat side.
The spring is possibly a spring bar that is arranged in a pivotably movable manner and whose one end is longer than the other end. The shorter end is in operative connection with the one valve ball or valve shutter of the valve, and the longer end enables the greater adjustment path and cooperates with the described adjustment mechanism. A sliding operative connection, known per se, is provided between the spring and the rotationally movable or pivotably movable part. This means that the spring slides on a surface of the rotationally movable or pivotably movable part of the adjustment mechanism.
The use of a spring bar that is designed as a two-armed lever arm is possible. The two-armed lever arm is hinged.
The operative connection with the valve ball or the valve shutter is created by the short end sliding against the valve ball or pressing against the valve shutter.
The operative connection with the adjustment mechanism is formed such that a sliding surface for the shorter lever arm is provided on the rotationally movable or pivotably movable part/rotor, and is designed as a curved path, on which the spring bar slidingly fits.
In some valves, the curved path runs in the circumferential direction and in the radial direction to the rotationally movable or pivotably movable part. The circumferential angle to the pivotably movable or rotatably movable part comprises for example at least three hundred degrees.
The spring defining the valve pressure can slide on the curved path in a pivoting direction/rotational direction or in both pivoting directions/rotational direction. The direction of movement is the result of the direction of rotation or pivoting direction of the rotatably movable or pivotably movable rotating part/rotor.
The rotatably movable rotating part/rotor can optionally be also moved further in the same rotational direction and nonetheless return to the adjustment beginning. This is achieved in that a connection is provided between the start of the curved path and the end of the curved path to the rotatably movable or pivotably movable part.
The rotatably movable or pivotably movable rotating part/rotor is seated on an axle/pivot/bolt that is formed integrally with the flexible cover or base of the housing. With the axle/pivot/bolt, the rotating part/rotor is rotatably movable or pivotably movable in the housing of the valve.
The spring defining the valve pressure slides on the rotatably movable rotating part/rotor and possibly has an angular shape. The two lever arms of the two-armed lever arm are at an angle to each other that is possibly less than one hundred eighty degrees and can also be less than ninety degrees.
The spring defining the valve pressure can have any cross section. Circular and rectangular shapes are possible. A spring with a leaf-shaped or wire-shaped cross section is possible.
A pin/axle/bolt, whose ends engage in suitable recesses in the valve housing or in the valve cover or valve base, is suitable for example for the rotatably movable or pivotably movable mounting of the spring that defines the valve pressure. The ends of the pin can also be pointed, such that the bar rotates on the tips in the recesses. This procedure is technically and economically possible.
To fasten the pin to the spring, a welded or soldered connection is suitable, as well as other types of connections.
For the spring defining the valve pressure to function it is possible if the long lever arm on the rotatably movable part or pivotably movable part (rotating part/rotor) of the adjustment mechanism is controlled. For that purpose this rotating part/rotor at the same time can control the spring defining the valve pressure on at least one side. On the other side the guide can be formed for example by a disk or by a membrane or by a housing cover or housing floor.
On the side of the valve ball it is possible if large area contact occurs between the spring defining the valve pressure and the valve ball. If the spring defining the valve pressure is not capable of touching this large area then a metal sheet can be fixed to the relevant end of the spring. The metal sheet is optionally welded on or soldered on or fastened in another way.
The rotating part/rotor is usually moved with magnets that are embedded into the rotating part/rotor. Hereinafter, the rotating part/rotor and the spring defining the valve pressure are referred to as the adjustment mechanism of the implanted valve. For adjusting the valve pressure an adjustment mechanism that is also provided with magnets is placed externally on the skin of the patient. These magnets of the externally placed adjustment mechanism interact with the magnets of the rotating part/rotor in the implanted valve, such that a rotation/pivoting motion of the externally placed adjustment mechanism brings about a rotation/pivoting motion of the rotating part/rotor arranged in the implanted valve. This results in an adjustment of the spring defining the valve pressure, linked with a change in the valve pressure.
The adjustment mechanism can also be involuntarily adjusted if the patient enters into the effective range of strong magnetic fields.
This led to the wish to lock the adjustment mechanism in each position. Various proposals have been made for locking.
Known proposals again use magnets for locking.
Other proposals use spring forces and frictional forces for locking.
In one proposal a housing in the locked state presses with cams in a friction locking manner onto the rotatingly movable rotor/rotating part that carries the oblique surface or staircase-shaped tiered surface, on which the above-described spring slides. For unlocking, the housing has to or should be curved in such a manner that the cams lift off from the rotor/rotating part. After the cams have lifted off, the rotor/rotating part can be adjusted with an adjustment mechanism that is located externally on the skin of the patient. This adjustment mechanism possesses magnets that interact with other magnets that are arranged in the rotor/rotating part.
In another proposal, the spring force of a curved housing cover is used for unlocking. The cover pulls the rotor/rotating part against it with its force resulting from the curvature, such that, in the locked state, the rotor/rotating part is friction-locked with the housing cover. Here, the rotor/rotating part is rotationally movably/pivotably movably seated on an axle/bolt provided on the housing cover.
For unlocking, the housing cover is deformed, such that the rotor/rotating part lifts off from the housing cover, the friction lock to the cover no longer exists and the rotor/rotating part can be pivoted with the help of an adjustment mechanism that is externally placed on the skin of the patient. The adjustment mechanism possesses magnets that are inserted into the rotor/rotating part.
Depending on the rotational/pivotable direction, the rotationally movable rotating part/rotor tightens or releases the spring that defines the valve pressure and which slides on the rotating part/rotor. In this regard, the spring defining the valve pressure slides on a curved path of the rotating part/rotor. At the same time the spring defining the valve pressure presses on the valve ball of the valve, such that a desired modification of the closing pressure of the valve ball or the valve occurs.
The valve ball interacts with a conical opening in the housing of the valve. In some valves, this opening is located on the inlet side of the valve.
The magnets possibly have a compact design, for example pin magnets are used. The small magnets also contribute to the compact dimensions of the valve.
The valve adjustment mechanism provided externally on the skin of the patient can likewise be designed with extremely small dimensions. In some valves, use is made of a reduced diameter and a possible shape of the adjustment device, namely designed in the shape of a pen, similar to a ballpoint pen. This allows the adjustment device to be handled as a pen or ballpoint pen, e.g. by carrying it in a breast pocket. At the same time the mechanism of a ballpoint pen is utilized in order to move the magnets provided in the head of the adjustment mechanism backwards or forward lengthways along the pen (with the applied pen, toward the head of the patient or toward the valve). In the vertical position of the pen, that means raising and lowering.
The pen-shaped adjustment device that is applied externally on the skin of the patient optionally possesses on the front end a cap, on which the adjustment device is placed. Loosely placing the adjustment device should automatically cause the magnets to center the adjustment device above the rotor/rotating part of the valve.
Once the adjustment device that is located externally on the patient has been centered on the implanted valve, provision is made for an elastic deformation of the implanted valve so as to unlock the rotating part/rotor. The above described adjustment is then carried out.